"North American engineers pored through every aerodynamic study they could find, looking for anything that could be applied to a large, triplesonic bomber. They came across a forgotten NACA (now NASA) research paper about "Compression Lift." This paper described how a conical body underneath the center of a wing would push the air to the side, increasing pressure under the wing section (thereby increasing lift!) "
http://www.labiker.org/xb70.html

Stealth was not an issue because there was nothing that could catch this monster at the time. She had the most unique bomb bay door system I have ever seen. The door slide back like a garage door on tracks. The bomb bay was huge, looks like an open cavern when standing underneath. The only one I have ever seen larger than the XB-70 was the B-36, but even the B-36 was not as wide only taller.
Anyone who has the chance to visit the AF Museum at Wright Patterson should take the opportunity to see this amazing bird.